1.2 Hydrosphere Flashcards
V shaped valley
Steep gradients force water to flow downslope and vertical erosion cuts down into valley
Vertical erosion is in form of hydraulic action- force of moving water breaks material off bank
Abrasion- scraping away of bed by transported material
Solution- chemicals in water dissolve minerals in rock
Vertical erosion exposes sides of valley from weathering and are weakened
De-stabilised rock falls into river and transported downstream, adds to erosive power of river
Overtime, a steep-sided V shaped valley forms with narrow walls
Resistant rocks found in upland areas means valley sides aren’t eroded greatly
When river meets hard, resistant rock it winds round it and takes path of soft rock
This leaves narrow necks of interlocking spurs that extend to either side of river valley
Waterfall
River moves over surface of resistant rock onto a layer of less resistant rock
Less resistant rock begins to erode quicker than resistant rock due to differential erosion, creating a step
River erodes from hydraulic action- force of moving water breaks material off bank
Abrasion- scraping away of bed by transported material
Solution- chemicals in water dissolve minerals in rock
River undercuts soft rock, leaving an overhang which is unsupported and falls into plunge pool
Rock swirls around in river which deepens plunge pool
Plunge pool is deepened most during high discharge when hydraulic action is most powerful
Waterfall retreats upstream and the process continues and a steep sided gorge is cut back into the hillside
Meander and Ox-bow lake
Lateral erosion occurs on outside bank of river due to water flowing flowing fastest as the bed is smoother
Outside bank erodes from hydraulic action- force of moving water breaks material off bank
Abrasion- scraping away of bed by transported material
Solution- chemicals in water dissolve minerals in rock
This gradually makes the neck of land narrower as two bends in river are eroded towards each other
The slower water on inside of bank causes deposition of material which creates a slip-off slope
Increased discharge will enhance erosion which then cuts through neck of land
Deposition seals off old meander bend which makes a new straight river channel
River takes the shortest route leaving old meander isolated, forming an ox-bow lake
This ox-bow lake eventually will fill up with sediment and dry up
Physical factors affecting hydrographs
Size- Large drainage basins catch more precipitation so have a higher peak discharge than smaller basins
Hydrological cycle within a drainage basin
Inputs: Precipitation is mainly through rain and snow
Intensity of the precipitation can affect this which could lead to increased surface run-off as the ground can’t absorb water quick enough
Outputs: Water is evaporated due to the heat intensity from the sun
Transpiration occurs when water is lost through the surface of vegetation and goes to the atmosphere
Storage: Water is stored in soil and vegetation as groundwater storage
Water reaches the groundwater storage by infiltration, when the water filters into the soil
Transfers: Water flowing over the ground is called surface run-off, when excess water can’t be infiltrated and could lead to flooding
Water intercepted by vegetation can be transferred by running down branches and stems as stemflow
Hydrographs- Physical factors
Relief: Steeper slope leading to river basin- water flows faster to the river
Vegetation: More vegetation intercepts rain- slows movement of water to the river
Size of river: Water reaches river quicker- smaller size of basin has less distance to travel
Rock: Impermeable rock reduces percolation- soil becomes saturated quickly
Hydrographs- Human factors
Urbanisation: More drains quickly deliver rain to the river- increases groundwater flow to river
Roads: Tarmac prevents infiltration as it is impermeable- creates fast surface run-off
Deforestation: Less trees in the area- doesn’t allow interception on vegetation
Agriculture: Compacted soils from farming reduces saturation in ground- prevents infiltration
